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Date May 2008 Marks available 2 Reference code 08M.2.sl.TZ1.3
Level SL only Paper 2 Time zone TZ1
Command term Find Question number 3 Adapted from N/A

Question

The diagram below shows a circle centre O, with radius r. The length of arc ABC is \(3\pi {\text{ cm}}\) and \({\rm{A}}\widehat {\rm{O}}{\rm{C}} = \frac{{2\pi }}{9}\).


Find the value of r.

[2]
a.

Find the perimeter of sector OABC.

[2]
b.

Find the area of sector OABC.

[2]
c.

Markscheme

evidence of appropriate approach     M1

e.g. \(3\pi  = r\frac{{2\pi }}{9}\)

\(r = 13.5\) (cm)     A1     N1

[2 marks]

a.

adding two radii plus \(3\pi \)     (M1)

\({\text{perimeter}} = 27 + 3\pi \) (cm) (\(= 36.4\))     A1     N2

[2 marks]

b.

evidence of appropriate approach     M1

e.g. \(\frac{1}{2} \times {13.5^2} \times \frac{{2\pi }}{9}\)

area \( = 20.25\pi \) (\({\text{cm}}^2\)) (\(= 63.6\))     A1     N1

[2 marks]

c.

Examiners report

Few errors were made in this question. Those that were made were usually arithmetical in nature.

a.

Few errors were made in this question. Those that were made were usually arithmetical in nature.

b.

Few errors were made in this question. Those that were made were usually arithmetical in nature.

c.

Syllabus sections

Topic 3 - Circular functions and trigonometry » 3.1 » The circle: radian measure of angles; length of an arc; area of a sector.
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